Ctrl + B bevel not beveling from center of edge
You look to be making a bevel of an already beveled edge, which isn't the same thing as beveling the two connected edges simultaneously. (That's probably the way to go.) If you want the two edges to be beveled to different widths, while containing the topology at the corner, you could do that with a Bevel modifier, by weight, and adjust the edge bevel weights, keeping an eye on the resulting topology. (Temporarily check 'Wire' and 'All Edges' in the object's display settings.)